The present invention relates to the production of coated abrasives and particularly to the production of such materials that are washable, that is to say can be cleansed from swarf collected on the surface during grinding by simply hosing off the surface.
The problems associated with accumulated swarf have been appreciated for many years, particularly in the wood grinding field. This is because of the relative softness of wood which permits much longer active life for a coated abrasive item than might be the case when grinding metal. In addition the development of abrasive grains with improved performance has added to the problem of swarf accumulation.
It has been known that certain additives, when coated on the surface of a coated abrasive, tend to reduce the swarf accumulation. It has been suggested that various polysiloxanes, metallic stearates and waxes might be used and these are all somewhat effective. However, they function by imparting a hydrophobic character to a surface that is usually hydrophilic, and as grinding proceeds, this coating is relatively easily displaced from the surface and the effect is significantly reduced.
It has now been discovered that, if an appropriate additive is used, the persistence of the hydrophobic coating can be made to equal or exceed the useful life of the coated abrasive product.